Considerations for Diagnosis & Treatment of Feline Bacterial Keratitis

Possible causes of feline keratitis include viral infection (ie, feline herpesvirus-1), eyelid abnormalities (eg, eyelid coloboma, agenesis, entropion, distichiasis, ectopic cilia, tumors), ocular trauma, ocular foreign bodies, corneal sequestra, and bacterial infection. Although bacterial keratitis is less common in cats as compared with other small animals, clinicians should consider the role bacteria can play in keratitis and know how to identify and effectively treat corneal bacterial infections.

This retrospective study of 81 cats (102 corneal samples) describes clinical characteristics of cats diagnosed with feline keratitis, as well as in vitro susceptibility patterns of corneal bacterial isolates. Most patients were presented with unilateral disease and exhibited blepharospasm and ocular discharge.

Gram-positive bacteria were most often cultured (82 out of 102 samples), with Staphylococcus spp isolated from 55% of samples. Most samples (62 out of 81 cats) contained a single bacterial isolate. All isolates were susceptible to ofloxacin; other effective in vitro antibiotics included ciprofloxacin, ticarcillin, gentamicin, and moxifloxacin. Although chloramphenicol and doxycycline were effective in vitro, the authors did not recommend them as first-line therapeutics due to their bacteriostatic activity. Overall success for maintaining vision and globe retention was very good (88%) in this study.

Key pearls to put into practice:

Bacterial keratitis is uncommon in cats. When present, gram-positive bacteria, particularly Staphylococcus spp, are the most likely infectious agents.

First-line antibiotics to treat suspected bacterial keratitis include ofloxacin, ciprofloxacin, ticarcillin, gentamicin, and moxifloxacin.

Judicial empiric use of antimicrobials is essential to prevent antibacterial resistance. Culture and susceptibility testing is recommended when possible.